Section: Verbal

27) You may wonder how the expert on fossil remains is able to trace descent through teeth, which seem ------ pegs upon which to hang whole ancestries.

1. reliable
2. inadequate
3. novel
4. academic
5. specious

If "you may wonder" how the expert reaches his conclusions, it appears that it is questionable to rely on teeth for guidance in interpreting fossils. Inadequate creates the element of doubt that the clause tries to develop.